Spray drying device



July 1 8, 1950 o. T. PIEPER- 2,515,665

SPRAY DRYING DEVICE Filed Sept. 11, 1946 2 Sheets-Sheet 1 INVENTOROliver I Pz'eyver BY W ATTORNEYS y 950 o. T. PIEPER 2,515,665

SPRAY DRYING DEVICE Filed Sept. 11, 1946 2 Sheets-Sheet 2 FIG. 4

INVENTOR filz'uer 7. Pie var ATTORN EYS Patented July 18, 1 950 OliverT. Pieper, Edgewood Hills, Del., assignor ,to American Dyewood Company,Chester, Pa., a corporation of Pennsylvania,

Application September 11, 1946, Serial No. 696,233

This invention relates to spray drying and particularly' to improvementsin apparatus for separating material in a dry condition from liquidscontaining such material.

Spray drying, in which a liquid is distributed into a current of heatedgas such for example as combustion products, with or without added air,for the purpose of rapidly evaporating the liquid and obtaining a dryproduct, has been practised for many years with various types ofapparatus. The most modern and eifective apparatus utilizes a whirlingdisc or wheel. to which the liquid is fed and from which it isdistributed by centrifugal force applied by the rapid rotation of thewheel. In such apparatus, the problem of obtaining proper distributionof the liquid from the wheel has never been completely solved. properdistribution of the liquid from the wheel has'resulted in failure toevaporate all of the liquid in portions of the material, and deposits ofpartially evaporated material are built up on the walls of theevaporation chamber. This in turnv necessitates frequent stoppage of theapparatus for cleaning and additional expense due to cleaning and to theloss of material which is not recovered in the desired form. Improperdistribution of the liquid from the wheel has also resulted inatomization of the liquid leaving the spray head, so that a mist ofliquidglobules is formed. Although such globules dryquickly and do notadhere to the walls of the drying chamber, they dry to form particles ofvery small size, which are objectionable, e. g., in soap powders wherethey cause discomfort to the user. These and other disadvantages of theknown types of apparatus have limited the application of spray drying,which in many cases has proved to be uneconomical.

It is an object of the present invention to provide an improved spraydrying head in which proper distribution of the liquid is maintained andthe disadvantages mentioned are avoided.

Another object ofthis invention is the provision of a spray drying headwhich is so designed that when rotated at high speeds (e. g, 5000-15,000 E. P. M.) it distributes into the drying chamber a substantiallyuniform sheet of liquid which is depressed in the form of an umbrella bythe stream of hot gas entering the drying chamber. For furtherinformation concerning the details of a complete spray drying apparatusin which the spray drying head of this invention maybe installed,reference is made to my prior patent applications serial Nos. 581,476and 581,- 477, filed March 7, 1945,1'10W Patent 2,478,779.

8Claims. (01.2995-63),

- These and other objects are accomplished in accordance with theinvention by constructing a spray dryinghead comprising a primary flangehaving a vertical circumferential baflle and a secondary or auxiliaryflange placed in such relationshipto the primary flange as to providean.

annular spacebetween them through which the liquid to be spray dried isthrown by centrifugal force. In accordance with this invention I havediscovered that it is essential that the outer circumferential face ofthe auxiliary flange should not extend above the adjacent inner verticalface Fig."1 represents in section an elevation of a circular spraydrying head having an external diameter of about 6 inches;

Fig.2 represents a modification of the primary flange by providing anintermediate baffle to assist inproviding a uniform sheet of liquidleaving the spraying device;

Fig. 3 represents a modification of the secondary or auxiliary flange,shown in relationship to the primary flange; and

Fig. 4 represents a sectional view taken on line 44 of Fig.v 1.

Referrin to Fig. 1,.the numeral l represents a rotatably mounted chamberto which the liquid to be spray dried is fed through the stationary pipe2 containing a control valve 3 to regulate the rate of liquid feed tothespray head 4. A series of radially'directed holes 5 is provided atthe base of the chamber l. The liquid being dried is thrown bycentrifugal force through these holes 5, then through the radialpassages 6 and 1 in theprimary flange 8, and then through the annularspaces 9 located between the primary flange 8. and the auxiliary flanges10. The auxiliary flanges l0 arespaced in such relationship to thevertical circumferential baffle II on the flange 8 so as to direct theliquid thrown through the annular spaces 9 against the baffle 11. Theliquid flows along the vertical face of the bafile H and is thencethrown in the form of a uniform sheet should preferably be staggered (asshown) and should be at least IS in number, in order to provide a liquidsheet having the greatest uniformity. The number of passages 6 and 1should not be so great, however, as to result in excessive weakening ofthe apparatus, and the passages should be of sufficient diameter toprevent their clogging. The number' and size of the passages 6 and Iwill depend upon the capacity desired for the apparatus, upon thematerials used in its manufacture, upon the liquid being spray dried,-and upon other factors, and may be determinedby simple experiments.

Referring to Fig. 2, an intermediate bafll'a I2- has been provided onthe flange 8; to assist in the production of a more uniform sheet ofliquid leaving the spray head and thus result ina reduction in thecontent of dust in the final product.

Fig. 3 shows a modification of the auxiliary flange H) which has beenfound to be useful in the preparation of a spray dried product ofdesirable properties. Preferably, however, the inner face: of the.verticalbaffle: H should extend 0000- 0.125: inch beyondithe adjacentface-of: the flange 10. Generally; the distance between the inner face:of' the vertical baffle H: and the outer edge of the: flange. II):should not be greater. than about A depending upon the rateoffeed ofthezliqe uid to theisprayhead'; uponthe particular liquid. being'spraydried, etc.

With a spray head of: the: type. described installed in-a suitabledrying'chamber, I have: eiflciently spray driedi many materials (e. g:,ex tracts. of quebracho; wattle; dividivi, logwood; fustic, licorice,and coffee, and solutions of'a' wide: variety of detergents) to producea free flowing, uniform product of high bulk' density containing aminimum proportion of products of. extremely small particle size.

I-claim 1. A- spray' drying device for distributin liq uid into a dryingchamber, comprising a rotate-- ably'mounted shaft having a-head securecithereto for rotationtherewith, andmeans. for conduct ing liquid to saidhead, saidhead" comprising an' outwardly-extending primar-y'flangeandtwo outwardly-extending auxiliary flanges all mounted: for rotationwith the head, the primary flange having smooth substantially planarupper and lower faces and the auxiliary flanges having smoothsubstantially planar faces spaced from the respective upper and lowerfaces of the' primary flange to provide upper'and lowera'nnul'archambers, said primary flange havingtransverse ly-extendi'ng upper andlower baffles. positioned beyond the outer peripheries of the auxiliaryflanges, said bafiles extending from said smooth faces of the primaryflange transversely-at least as far as the outer extremities of theauxiliary flanges, whereby liquid conducted to-the head: is thrown bycentrifugal force through the upper and lower annular chambers againstthe-upper? and lower baffles and along said bafiles into' the: dryingchamber in the form of asubstantially uniform sheet;

2 A spray drying device -as defined in claim I inwhich the primaryflange has a plurality of generally radially -ex-tendi'ng passages therethrough communicatingwithsaid annularch'ambers, and the body'of theheadhas'a-plurality'of 7 1 holes through which liquid introduced throughthe liquid conducti'ngmeans may-flowto said pas sages and to the annularchambers.

3; A- spray dr-yingd'evice as definediin claim. 1 in which the primaryflange has'anupperxand; at

.4 lower annular baffling face spaced inwardly of said outer bafiles.

4. A spray drying device for distributing liquid into a drying chamber,comprising a rotatably mounted shaft having a head secured thereto forrotation therewith, and means for conducting liquid to said head, saidhead comprising a primary flange substantially perpendicular. to saidshaft and mounted for rotation therewith, said flange having a hubportion with upper and lower faces, an intermediate portion of lessthickness than said hub portion having smooth substantially planar upperand lower faces and a baflle at its periphery extending: substantiallyperpendicularlyabove and below the intermediate portion, an

upper and a lower auxiliary flange mounted for rotation with the shaftand having smooth substantially planar faces contiguous to therespective upper and lower faces of the hub portion of the primaryflange over part of their extents and substantially parallel'but' spacedfrom the respectiveupper and lower faces of the intermediate portion ofthe primary flange. over. the remainder of their extents to provideupper and lower annular: chambers between the primary flange and theupper and lower auxiliary flanges and between. the hub and the baffle oftheprimary flange, said baiile being, positioned beyond the outer:peripheries-of! theupper and lowerauxiliary flanges-and extending fromthe. intermediate portiorr ofv the primary flange above. and belowperpendicularly at least. as far as the outer extremitieszofrthe upperandclower auxiliary flanges, respectively, and. a plurality ofpassageways. for

'- conducting liquid through said hub from the liquid.conducting-'means'to the upper. and lower annular chambers, wherebyliquid conducted to the head. is .thrown' by centrifugal force throughthe:

upper. andthe: lower annular'chambers against the. baffle and along" thebaffle into the drying chamber'in the. form of a substantially uniform.

sheet/L 5. Azspray: drying device as. defined in'claim 4 in. which saidpassageways extend alternately around the. peripheryofisaid hub portionto the upper/and; the'lower: annular chambers.

6-. A: spray drying device-for distributing liquid into: adrying:chamber, comprising a rotatably.

mounted shafthaving a head secured thereto for rotationv therewith, and:means for conducting liquidztosaid head, said head comprising anoutwardly-extending primary flange and an outwardly-extending. auxiliaryflange, both mounted for/rotation with the head, said flanges having.

smooth substantially planar annular opposing faces2spaced apart to forman annular chamber between. them, said. primary flange having atransversely-extending baffle positioned beyond but: adjacent' the.outer. periphery of said auxiliary flange,.saidl baffle-extending fromthe smoothfacexof said primary flange; transversely at least as farasthe outer: extremity of the auxiliary flange, whereby liquid: conductedto. the head is thrown bycentrifugal force through said annular chamberagainst said baffle and along said bafiie into the drying chamber invtheform of a sub-- stantially uniform sheet;

7.. Alspray'drying device as defined in claim 6 in which the primaryflange has a plurality of generally radiallyextending, passagestherethrough communicating with the annular cham-- ber; and the body ofthe head has a plurality of holes. through which liquid introducedthrough the liquid conducting means may flow to said passageszandto theannular chamber,

8. A spray drying device for distributing 1iquid into a dryin chamber,comprising a rotatably mounted shaft having a head secured thereto forrotation therewith, and means for conducting liquid to said head, saidhead comprising an outwardly-extending primary flange and anoutwardly-extending auxiliary flange both mounted for rotation with saidhead, said flanges having smooth substantially planar opposing facesspaced apart to form an annular chamber between them, said primaryflange and said auxiliary flange each having a second face at the outerperiphery of the respective first-mentioned faces extending transverselythereof and spaced relative to each other to provide a discharge channelcommunicating with the drying chamber, the second face of the primaryflange being mounted beyond the second face of the auxiliary flange andextending transversely from the first face of the primary flange atleast as far as the outer extremity of the second face of the auxiliaryflange, whereby liquid conducted to the head is thrown by centrifugalforce through said annular chamberagainst the second face of the primaryflange and through said channel into the drying chamber in the form of asubstantially uniform sheet.

OLIVER T. PIEPER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 442,865 Kinder Dec. 16, 18901,779,296 Spross Oct. 21, 1930 1,779,336 Riley Oct. 21, 1930 1,870,099Croan Aug. 2, 1932

